         :else (recur (walk ds E j i))))))
 
 (defn orbit-loopless? [ds indices D]
-  (empty? (for [[D i] (pretty-traversal ds indices [D])
+  (empty? (for [[D i] (traversal ds indices [D])
                 :when (and (not= i :root) (or (nil? D) (= D (s ds i D))))]
             D)))
 

      (let [idcs (indices ds)]
        (reduce lexicographically-smallest
                (for [D (elements ds)]
                  (protocol ds idcs (pretty-traversal ds idcs [D]))))))))

(defn walk [ds D & idxs]
  "Returns the result of applying the D-symbol operators on ds with the

                           head (if (= i :root) [-1] [(imap i) Ei])
                           tail (if new? (spins D) [])]
                       (concat head [E] tail (step xs emap n)))))))]
    (step trav {} 1)))

(defn invariant [ds]
  (do
